In health care, there has been an increased emphasis on more widespread use of diagnostic tests involving biological fluids, especially in the area of infectious diseases. Administering treatment in the fashion referred to as “therapeutic trials” rather than one based on a clear etiology is becoming more disfavored all over the world. There are several key disease related targets of interest including: nucleic acids, proteins, and metabolic signatures either individually or in combination with each other. Of particular importance are the antibody based tests, since they are well established as very specific and powerful for a wide range of disease detection. Since the basic need of a diagnostic test in general is for a rapid, inexpensive, convenient, and accurate decision making method that can advise whether to begin therapy, one step antibody tests have been developed for several decades and continue to have expanded applications in many different formats.
The current antibody based, in vitro diagnostic technologies (IVDT) vary from the elegantly simple lateral flow immunoassays to instrument intensive systems such as ELISA. While lateral flow assays are inexpensive and mobile and can serve many needs due to their reasonable sensitivity, they have many drawbacks. On the other end of the spectrum, manual microplate or robotic immunoassays with special fluorescent or chemiluminescent markers provide greater sensitivity, quantitation, documentation of results, and higher specificity. The emerging technology of microfluidic immunoassays are focused on retaining the benefits of microplate/robotic systems while providing portability, decreasing sample size, enhanced automation, and lowering costs. However, commercial systems have been slow to develop since microfluidics and associated technologies are in early stage development, in part since miniaturization poses new challenges in choice of materials, control and detection equipment, and operability.
What has not been investigated much or developed, are hybrid platforms that make use of natural driving forces while employing low power, simple instrumentation for improved sensitivity, quantization, and documentation. Interestingly, readers for lateral flow systems have recently become more popular in order to improve sensitivity and avoid misinterpretation by human readers. While companies are increasingly making them available for their specific lateral flow format, this approach does not represent a holistic approach to integrating natural driving forces with instrument based interpretation of the biological recognition event.